We're sorry—are you still unfamiliar with what mixed martial arts is? Because basically the answer here is "duh." If you walk away from the cage unscathed, you're probably the referee (and even then, your chances of an injury are pretty high).
This isn't just because of the general nature of being in a fight. MMA fighters are highly trained individuals who know how and where to strike opponents to maximize the risk of serious injury. They're also in fantastic physical shape, so the amount of energy they're able to use is so massive it'd give NASA physicists a headache. And let's not forget that some fighters are well-versed in pulling on your joints and limbs until you give up or pass out.
Horrifying injuries don't happen to every fighter, but they can happen to any of them, during any bout. We're not talking minor scrapes and bruises here—from broken bones to concussions to paralysis, anything's possible when your body is doing all the work.
So is that desk job still sounding like a bad idea?